Hello,
The CQ-12T has only 2 FX units, but those units can be populated with any of the available FX as needed. The CQ-18T, and CQ-20B have 4 FX units, and again those 4 slots can be populated with any FX unit that you choose. The FX are quite easy to use on the CQ and sound good, and the option buttons do change the character of the effect in question.
So far, I think the knob controls only react to left/right movement, but since that is a software thing, that can change in the future. The same thing is true of the DB scale on the sends. They’re not there yet, but could be at some point in the future.
For #5 I can’t say at this moment, as I haven’t tried to do this.
Presently there are no side chain options.
The LISTEN is the PAFL bus, which can be toggled with the little headphone buttons on each channel that you mentioned. These aren’t active when in demo mode in the app.